This invention relates to a cassette loading/unloading apparatus for cassette tape recorder.
In a slot-in type cassette tape recorder utilizing a toggle spring, a cassette is pushed into a cassette holder against the biasing force of the toggle spring at cassette insertion until it reaches the neutral point of the toggle spring. When the neutral point of the toggle spring is passed, the biasing force of the toggle spring acts so as to draw the cassette in the cassette holder, and thus the cassette is instant drawn into the cassette holder. The stroke of the cassette terminating at the neutral point of the toggle spring is called pushing-in stroke, while the stroke starting at the neutral point is called drawing-in stroke. The length of each stroke is proportional to the biasing force produced in the toggle spring. If the drawing-in stroke is large, the biasing force of the toggle spring to act after the cassette is drawn in the cassette holder may be set at a high level, so that the cassette can be loaded securely. If the psuhing-in stroke is large, on the other hand, the biasing force of the toggle spring to act as an ejecting force at cassette ejection may be set at a high level, so that the cassette ejection can be ensured.
Since the biasing force of the toggle spring acts as a resisting force against cassette insertion in the drawing-in stroke, it is not advisable to make the drawing-in stroke very large. If the drawing-in stroke is too small, on the other hand, it will be started before the cassette will be held satisfactorily in the cassette holder, failing to ensure steady cassette loading. Namely, for secure cassette loading, it is necessary that a proper resisting force be applied to the cassette in the pushing-in stroke.
In general, the toggle spring is so disposed that the pushing-in and drawing-in strokes are equal in length. There are known two types of cassettes; compact cassette and micro cassette whose surface area is approximately 1/4 of that of the compact cassette. With the compact cassette, which is relatively large-sized, both strokes can generally be large enough to ensure both cassette insertion and ejection. With the micro cassette, however, neither of the strokes can be large due to the limited cassette size. In some cases, it is difficult to make the strokes large enough even with the compact cassette because of the positional relations with other members and limited space.
Staar and counter-Staar type cassette tape recorders are known as slot-in type cassette tape recorders.